Stages of erythropoiesis

1. STAGES OF
ERYTHROPOIESIS
BY:
ABHISHEK BHARTI

2. DEFINITION
oErythropoiesis is the process of
origin,development and maturation of
erythrocytes from primitive stem cells.

3. Sites of Erythropoiesis
IN FETAL LIFE
1. MESOBLASTIC STAGE: During the first two months
of intrauterine life ,the RBCs are produced from
mesenchyme of yolk sac.
2.HEPATIC STAGE: From third month of intrauterine
life,the liver is the main site of production of RBCs. Spleen
and lymph node are also involved.
3.MYELOID STAGE: During the last three months of
intrauterine life RBCs are produced from red bone marrow
and liver

4. AFTER BIRTH
In children
All bones with red bone marrow
Liver & spleen
In adults (after 20yrs)
Ends of long bones
like femur, humerus
Skull, Ribs
Sternum
pelvis

6. STEM CELLS
These cells have extensive proliferative capacity
and also the:
Ability to give rise to new stem cells (Self
Renewal)
Ability to differentiate into any blood cells lines
(Pluripotency)
Pluripotent Hemopoietic stem cells (PHSCs)
are bone marrow cells that are capable of
producing all types of blood cells.
They differentiate into one or another type of
committed stem cells (progenitor cells).

7. Commited pluripotent hemopoietic stem cell
When the cells designed to form a particular type
of blood cell,the uncommited PHSCs are called as
committed pluripotent hemopoietic stem cell.
Committed PHSC also further divided into
lymphoid and colony forming blastocytes.
Colony forming blastocytes are of three types:

9. Changes during erythropoiesis
1.Reduction in size of cell
2.Disappearance of nucleoli and nucleus
3.Appearance of haemoglobin
4.Changes in the staining properties of the
cytoplasm .

10. 1.Proerythroblast
• 15-20 microns in size
• Nucleus with two or more
nucleoli
• Basophilic cytoplasm
• Synthesis of hemoglobin
begins in this stage but
appearance occur only in
third stage

11. 2. Basophilic/ early normoblast
• Slight reduction in size 14-
17µm
• In the nucleus ,the nucleoli
disappear
• Condensation of
chromatin fibers occurs
• Cytoplasm is basophillic

12. 3.Polychromatophilic/ intermediate
normoblast
10-15µm in size
POLYCHROMATIC
PROPERITES
nucleus further
condenses
Hb starts appearing

13. 4. Orthochromatic / Late
normoblast
•7-10µm
•Acidophilic cytoplasm
•Nucleus becomes very small
with much condensed chromatin
•Nucleus disintegrates and
disappear by the process of
pyknosis before it passes to the
next stage

14. 5. Reticulocyte Reticular nuclear
fragments
Slightly larger than RBCs
Acidophillic cytoplasm
Cells enter blood
capillaries by diapedesis
The number of
reticulocytes increase
when production of
RBCs increase.

15. 6. Mature erythrocyte
• Reddish, circular,
biconcave cells
•
•
•
• 7.3 µm in size
No visible internal
structure
High Hb content
Bright at centre due
to biconcave shape
7.3 µm